ultra 80 power up , 3 second get low beep

There may be something else to consider.
The U-80, the 420R, and the Netra 14xx systems share that systemboard.
RAM is populated to slots on the systemboard and to slots on a RAM riser card.
Half of each memory bank goes to each, as described in the PDF manual that
Harold linked you to, earlier.

If the RAM riser board isn't perfectly torqued into place, the system will not boot.
For that workstation form factor computer, it would be best for you to work on it
while the box is on its side, not in its original up/down operational position.

Remove the RAM riser, remove and reseat each DIMM, then re-install the riser board.

Again, the board is to be installed to a specific torque level, and not
to whether it appears tight or loose. Over-torquing can destroy the slot it goes into.